SCS Engineers is proud to announce that Eric Peterson, PE, Vice President and Director of the firm’s Medford, New Jersey office, will be honored with the SWANA Landfill Gas & Biogas Technical Division Distinguished Individual Achievement Award at RCon in September.
The award recognizes long-term service to the landfill gas and biogas industry, contributions to SWANA’s mission of transforming waste into a resource, service to the Landfill Gas & Biogas Technical Division, and meaningful contributions to one’s employer and the broader solid waste management field.
Eric said. “I am delighted and honored to receive this recognition from SWANA for my 40-plus years in the landfill gas industry. I’ve enjoyed working in this multifaceted industry, which has afforded me the opportunity to advance practical solutions for methane migration, fugitive emissions, odor control, energy recovery, and public health and safety. The vibrant SWANA landfill gas division has also been a great resource for collaboration and camaraderie.”
Peterson has spent his career helping landfill owners and operators turn environmental challenges into practical, economically viable clean-energy and compliance solutions. His work includes the design of more than 200 landfill gas recovery and control systems; technical and financial due diligence for renewable natural gas and energy projects; methane mitigation, odor control, and hydrogen sulfide treatment; and strategies for managing deep and high-liquid landfills.
“Eric represents the best of SCS Engineers and the landfill gas profession,” said SCS CEO Doug Doerr. “He combines deep technical knowledge with a practical understanding of what facility owners, communities, regulators, and clean-energy investors need to succeed. His work has helped make landfill gas recovery more reliable, more affordable, and more valuable as a renewable energy resource.”
A longtime contributor to SWANA, Peterson has supported the organization through technical education, chapter leadership, committee participation, and landfill gas training. He has helped develop and share best practices that improve gas-capture efficiency, strengthen compliance, and advance the industry’s ability to convert waste-generated methane into usable energy.
Peterson’s influence also extends internationally. He has presented at seminars and conferences supporting landfill gas, biogas, and emissions management in multiple countries. He has helped apply U.S. regulatory and engineering expertise to international landfill emissions programs.
At SCS, Peterson has played a key role in standardizing landfill gas technical practices across the firm, mentoring emerging engineers and scientists, and expanding the company’s landfill gas, biogas, odor control, renewable energy, and due diligence services. Colleagues describe him as a careful listener, thoughtful collaborator, and steady technical leader whose mentorship has helped shape the next generation of environmental professionals.
Please join us in congratulating Eric on this well-deserved honor and thanking him for his lasting contributions to SCS Engineers, SWANA, and the landfill gas and biogas industry.
Senior Vice President Pat Sullivan announces a key leadership transition; Vidhya Viswanathan, previously SCS’s Director of Engineering in the Southwest, now assumes responsibility for the strategic direction and operational oversight of the Solid Waste Group, including the Engineering, Sustainable Materials Management, and Permitting and Compliance teams.
Vidhya has significantly advanced SCS’s solid waste engineering operations across the Southwest and influenced industry standards nationwide. Her leadership in technical areas like landfill gas engineering and composting demonstrates her exceptional expertise and dedication.
Vidhya began her career with the City of Lawton, Oklahoma, joining SCS in 2012 as a Young Professional and recognized regionally and nationally with prestigious awards. Now an SCS mentor with 20 years of experience in the solid waste and environmental consulting industry, she shares her knowledge and skills with young staff members as she progresses through leadership roles at SCS, including Senior Vice President and SCS Board Member. She is a licensed Professional Engineer in California, Arizona, Nevada, and Oklahoma and is based in SCS’s San Diego office.
Vidhya exemplifies the next generation of SCS leadership, combining strong technical expertise, a commitment to quality, and a proven ability to develop teams and deliver exceptional client service. Her vision and leadership are poised to enhance our service offerings, strengthen industry collaborations, and support SCS’s continued top ranking by ENR in the Waste Management industry.
Please join SCS in congratulating Vidhya on her promotion and new leadership role. We look forward to her guiding strategic initiatives that will advance our industry expertise and client solutions in the coming years.
SCS Engineers announces two leadership changes in its Southwest solid waste and engineering divisions. The firm promotes Eric Sonsthagen, P.E., to Project Director and Engineering Lead. After a transition period from Srividhya (Vidhya) Viswanathan, P.E., to Eric, Vidhya will lead the solid waste group.
As part of the Southwestern Business Unit’s broader leadership plan, SCS Engineers will transition several senior roles over the next 18 months to support the next generation of company leaders. Senior Vice President Patrick S. Sullivan, REPA, CPP, BCES, said the company designed these transitions to position SCS and its clients for continued growth and long-term success.
Eric Sonsthagen brings two decades of experience leading environmental and solid waste projects for public and private clients. He designs, reviews, and permits solid waste facilities; oversees landfill gas control and mitigation systems; modifies gas collection and control systems; and manages landfill cell construction and closure projects.
As Project Director and Engineering Lead, Sonsthagen will work across SCS’s specialty business divisions, drive project execution, strengthen the engineering division, and advance strategic priorities. He adds deep expertise in landfill gas engineering and modeling, beneficial reuse evaluations, air permitting, emissions inventories, compliance evaluations, and environmental investigations.
Vidhya Viswanathan currently serves as Senior Vice President and Director of Engineering for SCS Engineers’ Southwest region and will assume leadership of the solid waste group. She has more than two decades of experience in solid waste management, landfill gas engineering, and compost facility design. She is a licensed Professional Engineer in California, Arizona, Nevada, and Oklahoma and is based in San Diego, CA.
“These are important leadership transitions for the next generation of SCS leaders and to assure continued quality delivery for our clients,” Sullivan said.
Drones monitor and measure landfills, pipelines, and solar farms.
The California Air Resources Board (CARB) is amending its Landfill Methane Regulation (LMR) to strengthen landfill compliance and meet the state’s target of reducing methane emissions by 40% by 2030. The rules target steep emissions reductions through enhanced surface monitoring, including drone-mounted scanners, robotic sensors, and remote monitoring, as well as stricter wellhead thresholds, among other measures.
The CARB-proposed amendments will have significant impacts on landfill and gas collection and control systems (GCCS), for which owners and operators will need to plan and implement to meet the requirements. As the nation’s top engineering specialist firm in this sector (ENR Solid Waste and Environmental Sourcebook), SCS Engineers has prepared articles and videos to assist landfill owners/operators in complying with these new requirements, including proactive measures that can be deployed to minimize impacts, planning for additional staffing support to complete all of the new monitoring, new or modified GCCS equipment and other infrastructure that will be needed, and new technology necessary to meet new deadlines.
As essential services, or any business for that matter, the changes require additional budget and capital investment to meet extensive surface and leak-monitoring and repair protocols, tighter regulatory timelines for installing GCCS, and more frequent and extensive monitoring and analysis of cover integrity, temperature, oxygen, and liquid levels.
Planning begins now.
SCS’s first article summarizes the key changes and highlights the most salient points of the revised LMR. The companion educational video and slide set are available free of charge to the public and can serve as a starting point for owners, operators, compliance staff, field technicians, and engineers in landfill and gas management, including energy recovery and renewable natural gas facilities.
CARB Landfill Methane Regulations Free Resources:
Paper detailing the technical changes and summarizing salient steps.
Educational video provides a detailed overview of CARB’s landfill methane rule amendments, with actionable recommendations for landfill operators and compliance teams to assess site status, plan for new requirements, and budget for anticipated operational and capital changes.
As demand for securing domestic sources of critical minerals grows, mapping and quantifying their geologic sources is more important than ever. These critical minerals often escaped notice during historical exploration because attention was focused on commodity metals (e.g., gold, silver, copper), and their concentrations are often significantly lower than those of the precious metals. Exploratory drilling can help significantly close the gap in critical mineral data scarcity across the nation, reducing risk from both technoeconomic and environmental standpoints.
Let’s look at a project in Missouri. The Missouri Geological Survey has expanded its efforts to better understand the subsurface geology as it evaluates formations that may contain rare-earth elements and other strategic resources. These broader state efforts reflect a growing nationwide focus on geologic mapping, core preservation, and resource evaluation to find and quantify critical minerals in the U.S.
Our SCS Critical Minerals team, along with HAD, Inc. drillers, recently supported one of these efforts through deep bedrock coring designed to collect high-quality, continuous core for geologic characterization, resource assessment, and long-term archival use. The work included coordinating safe drilling operations, overseeing continuous core recovery, and supporting lithologic logging and field documentation.
The SCS team helps extract reliable subsurface data from deep bedrock intervals, including dolomitic units and underlying Precambrian formations, strengthening our understanding of mineralization potential and the geology of the Viburnum Trend. Data from this drill core will help to identify what critical minerals may be present, how they occur, and in what concentrations– all of which are essential to evaluate their potential for recovery and utilization.
The Missouri Geological Survey will analyze each core for critical mineral and rare-earth element concentrations using a suite of analytical tools, including x-ray fluorescence (XRF) scanning and other geochemical characterization methods. These data will help researchers better understand what elements are present, how concentrations vary with depth and geology, and how mineralization occurs within the subsurface.
Projects like this highlight the value of integrating drilling, coordination, geologic interpretation, and resource-focused evaluation into a single, well-executed field program that can be recreated across the U.S. As public and private stakeholders invest in domestic critical minerals and energy transition initiatives, we support efforts to turn subsurface data into actionable information to determine resource value and profitable extraction techniques while meeting rigorous mining regulations for environmental protection.
Mining is one of the most highly regulated and environmentally sensitive industries in the U.S. At the same time, federal and state priorities emphasize the strategic importance of domestic rare earth element and critical mineral production, both from conventional and, increasingly, unconventional resources. Learn more here, or contact one of our National Experts!
Environmental compliance in printing operations involves complex interactions between materials, production processes, and regulatory permits. Small operational changes, such as material substitutions, can significantly affect emissions calculations and compliance status, even if they seem minor.
Material changes affect compliance: Switching to materials with different VOC or hazardous air pollutant contents can increase a facility’s potential-to-emit (PTE), requiring updates to emissions calculations and permit conditions. These impacts often go unnoticed on the production floor but can create compliance risks later during inspections or reporting.
Emissions driven by mass balance: Printing air programs calculate emissions based on material usage multiplied by VOC/HAP content, adjusted for capture and control efficiencies. This approach offers operational flexibility but also introduces complexity, as small formulation changes directly affect emissions.
Material substitutions are common and risky: Frequent substitutions under supply chain pressure can alter VOC content, HAP speciation, vapor pressure, and control device assumptions, impacting emissions and permit compliance if not evaluated in advance.
Potential-to-Emit (PTE) is critical: Regulators focus on PTE, which considers maximum emissions under full operation. Changes in VOC content or production capacity can increase PTE, potentially breaching permit thresholds, especially for facilities operating under synthetic minor limits.
Operational drift from permit assumptions: Over time, facilities may shift materials, usage rates, or production levels without updating permits, leading to unintentional non-compliance despite ongoing emissions tracking.
Recordkeeping is foundational: Maintaining accurate VOC/HAP usage records, emissions calculations, control device data, and hazardous waste documentation is essential to demonstrate compliance during inspections and avoid issues arising from misaligned documentation.
Best practices for compliance management: Effective facilities integrate environmental reviews into change management, align operational and emissions data, keep permit limits visible to operations, establish material approval processes, involve environmental expertise early, and periodically recalibrate permit assumptions to prevent compliance gaps.
Salt Lake City’s rapid growth is expanding into areas affected by historic mining, where mine tailings—residual materials from ore processing—pose environmental and financial challenges. However, these tailings do not inherently preclude development; rather, they should be treated as specialized brownfields that can be safely redeveloped through informed due diligence and risk-based planning.
Understanding Mine Tailings in Salt Lake City’s Growth
Utah’s long mining history has left tailings spread across large areas, which were historically viewed as inert fill but now lie beneath or near expanding development corridors. These tailings are a common due diligence concern in real estate transactions, yet misconceptions about their impact can lead developers to overestimate remediation needs. Many tailings-affected sites can be redeveloped successfully using established environmental and engineering methods.
Mine Tailings as a Unique Brownfields Remediation Condition
Mine tailings qualify as brownfields—previously disturbed lands with environmental concerns—but differ from typical urban brownfields. Unlike discrete contamination sources, tailings are shallow, widespread, and usually contain elevated levels of metals such as arsenic, lead, cadmium, or mercury, spread uniformly across large areas. This lateral, shallow nature supports practical, risk-based solutions that focus on exposure management rather than full removal, protecting human health while controlling costs.
Regional Redevelopment Examples
Across the Salt Lake Valley, various redevelopment projects illustrate that mining legacies do not preclude development. Large master-planned communities, urban infill projects, former rail and industrial corridors, and river-adjacent developments have all successfully addressed historic environmental constraints by combining thorough planning, engineered controls, soil characterization, and exposure pathway evaluation. These examples demonstrate that early investigation and regulatory coordination enable routine and feasible brownfields redevelopment, including sites with mine tailings.
Due Diligence and Site Assessment
Effective redevelopment begins with comprehensive due diligence. Phase I Environmental Site Assessments identify historical mining or smelting activities through historical maps and records. If environmental concerns are found, Phase II investigations focus on soil metals characterization, the extent of impacted materials, and exposure pathways relevant to the proposed land use. These assessments inform feasibility assessments, cost estimation, site design, and purchase negotiations, reducing uncertainty and avoiding surprises later.
Utah’s Risk-Based Regulatory Framework
Utah employs a risk-based regulatory approach allowing tailored cleanup strategies based on site conditions and intended land use. Residential projects face stricter exposure standards than commercial or industrial uses. Common regulatory measures include engineered barriers (e.g., clean soil caps, pavement), construction soil management plans, and institutional controls that document site conditions and obligations. Voluntary cleanup programs offer regulatory certainty and liability protection, integrating environmental measures into project design rather than treating them as separate remedies.
Integrating Environmental Planning into Brownfields Remediation
Successful projects integrate environmental planning with civil engineering, grading, and construction sequencing. Tailings can be managed beneath building footprints, roads, or landscaped areas, acting as engineered caps. Excavated materials can sometimes be reused on-site under controlled conditions to reduce costs and traffic. Construction-phase soil management plans help contractors efficiently handle impacted soils, minimizing delays. This approach makes environmental considerations a manageable design parameter.
Managing Risk and Financial Considerations
Uncertainty is a major risk in brownfields redevelopment. Early characterization of tailings reduces uncertainty, enabling accurate cost modeling and contingency allocation. Additional risk-management tools include environmental insurance, negotiated purchase terms that reflect known conditions, and phased development strategies that spread cleanup costs over time. Sellers often price brownfields below market value due to perceived complexity, thereby giving knowledgeable developers a competitive advantage.
Importance for Salt Lake City’s Future Growth
Mine tailings are a distinctive redevelopment challenge in the Western U.S., with Salt Lake City central to this issue. As growth continues, the number of mining-impacted sites could increase. The key is not whether development can occur, but how thoughtfully and efficiently these sites are approached. Viewing mine tailings as brownfield opportunities rather than obstacles helps us unlock strategically located land while protecting health and the environment.
Conclusion: Key Takeaway
Mine tailings should not lead to project abandonment; instead, they should prompt early, informed inquiry, engagement of experienced professionals, and integration of environmental planning into development. Through due diligence and risk-based cleanup, tailings-impacted sites can support safe, vibrant, and profitable redevelopment that meets Salt Lake City’s growth goals and those of other states with similar conditions, such as Texas, New Mexico, and Nevada.
About the Author: Thomas (Tom) Gordon, EP, serves as a senior project manager with SCS Engineers in Salt Lake City and can be reached at SCS Engineers. He specializes in environmental due diligence, brownfields redevelopment, and risk-based cleanup strategies that support development projects across the region.
Additional Brownfields Remediation Resources:
How Will Radon Testing Impact My Development Project? Nationwide, enhanced standards, which took effect for loan applications after June 30, 2023, aim to improve air quality, with some 2025 updates beginning to refine these requirements. Recently, significant tightening of …
Brownfields and Voluntary Remediation Brownfields and voluntary remediation projects protect human health and the environment while restoring properties to beneficial use. SCS Engineers is a pioneer in supporting public-private partnerships for this type of redevelopment …
A recent examination by SCS Engineers Project Directors Evan Guignon, PE, and Michael Bradford, PE, into geosynthetic liner damage and repairs examined the permeability of geosynthetic liners used in waste containment systems. Their blog focuses on the significance of lined containment, the perception versus reality of liner permeability, liner installations, and liner repairs.
Importance of Lined Containment
Lined containment is crucial for managing solids, liquids, and gases in waste containment systems. Over the past 50 years, regulations such as CCR Title 27, Title 40 CFR, and RCRA (Subtitle D) have emphasized the need for effective containment.
Liner Permeability: Perception vs. Reality
The common perception is that geomembrane barriers are impermeable and that lined ponds are watertight. However, even a “perfect” liner will leak through diffusion. The leakage rate is influenced by the head over the liner, ranging from 1 to 8 gallons per acre per day for a standing head of 1 to 10 feet deep.
Minimizing Leaks: Liner Installations
Successful liner installations involve multiple stakeholders, including manufacturers, installers, design engineers, Construction Quality Assurance (CQA) engineers, and laboratories. Common defects and damages during installation include manufacturing defects (e.g., needle holes), installation errors, equipment damage, and issues with waste/material placement. CQA (Construction Quality Assurance) engineers play a vital role in minimizing these defects and ensuring the liner’s integrity.
Detecting and Managing Leaks
Single-lined facilities use groundwater or soil gas vapor monitoring wells to detect leaks. Dual-contained facilities use leak detection systems called pan lysimeters. The EPA Action Leakage Rate (ALR) recommends 1,000 gallons per acre per day for ponds and 100 gallons per acre per day for landfills. States can set their own ALR values based on the type and function of containment. If leaks exceed the ALR, inspections and repairs are performed to address liner containment.
Liner Repairs
When damage occurs to ponds or cells, repairs are necessary. Damage can be internal (e.g., wrinkles, creases) or external (e.g., rocks, operations, environmental factors). Long-term UV exposure, catastrophic events (e.g., fire or wildlife), and slope stability failures can also cause damage. Repair solutions for ponds and impoundments involve draining, cleaning, and replacing or repairing the liner. The process for cells includes exposing them, cleaning them, and repairing or replacing the liner.
Geosynthetic Liner Conclusion
The design, material manufacturing, installation, CQA services, lab testing, and leak/damage monitoring all contribute to the overall effectiveness of the containment system. CQA, with continuous monitoring and timely repairs, is essential to maintaining the integrity of these systems.
About the Authors:
Evan Guignon, PE has experience with semiannual reporting, exceedance tracking, and regulatory compliance related to environmental projects. He has training in AutoCAD Civil 3D Advanced Landfill Grading Applications and Plant 3D Modeling. Evan’s background includes stream restoration design planning and research involving cement sample preparation and testing according to ASTM standards. Mr. Guignon holds multiple state Professional Engineer licenses.
Michael Bradford, PE brings over 20 years of experience in civil engineering and project management, specializing in solid waste landfill and public works projects. His expertise includes landfill site planning, excavation and grading design, stormwater management, geosynthetic liner design, landfill gas collection and control systems, and leachate recovery system design. Mr. Bradford has managed large-scale landfill expansions and closure projects, including permitting and construction quality assurance, and holds multiple state Professional Engineer licenses as well as CQA/CQC certification for geosynthetic materials inspection. His work includes managing permit modifications and landfill expansions that extended facility life by decades, demonstrating his capability in regulatory compliance and technical leadership.
Evolving Geosynthetic Clay Liners and Coal Ash, Waste360, Eric Nelson of SCS and EREF Researcher Kuo Tian discuss polymer-modified Geosynthetic clay liners that can manage aggressive leachate and meet EPA’s requirements. The polymer-modified alternative system is a sustainable …
Practical Implications for Industrial and Solid Waste Facilities and the Real Estate Industry
Following the EPA’s announcements on PFAS/PFOS destruction and disposal since 2023 and the most recent Interim Guidance in April 2026, trends indicate widespread implications for industrial facilities, the real estate industry, and the solid waste and wastewater industries. PFAS controls and liability frameworks under CERCLA/Superfund and RCRA are tightening rather than rolling back, increasing compliance planning, monitoring, and litigation risk.
EPA finalized CERCLA hazardous substance designations for PFOA and PFOS (including salts and structural isomers) in April 2024; the rule took effect in July 2024 and is being defended by EPA amid ongoing D.C. Circuit litigation.
EPA is evaluating whether to designate seven additional PFAS as CERCLA hazardous substances (PFBS, PFHxS, PFNA, HFPO–DA/GenX, PFBA, PFHxA, and PFDA), following an April 2023 ANPRM.
For facilities and real estate transactions, the PFOA/PFOS CERCLA designations can affect Phase I ESA expectations, PRP determinations, closed-site reopeners, and release reporting; releases of ≥1 pound in 24 hours trigger CERCLA/EPCRA reporting obligations.
EPA proposed listing nine PFAS as RCRA hazardous constituents in February 2024 and intends to finalize the rule in 2026, which could expand corrective action obligations for generators and TSDFs with relevant solid waste management units.
In April 2026, EPA updated its interim guidance on PFAS/PFOS destruction and disposal (Version 2, April 2024), identifying options with lower potential for environmental release, such as permitted Subtitle C hazardous waste landfills, permitted hazardous waste combustors, and permitted Class I injection wells. SCS Engineers has prepared an SCS Technical Bulletin to walk our clients through the announcements and discuss the impact and trends.
The U.S. Environmental Protection Agency (USEPA) has issued guidance to simplify the Title V operating permit renewal process, emphasizing administrative efficiency while maintaining full compliance obligations. The guidance encourages focusing on changes rather than resubmitting unchanged information, but facilities must remain vigilant as renewals can reveal unresolved compliance issues.
Streamlined renewal process: The guidance permits the use of previously submitted materials, incorporation by reference, and directs agencies to concentrate on changes, without altering regulatory or compliance requirements.
Renewal as compliance check: Even if operations are unchanged, renewals prompt reassessment of assumptions, monitoring, and applicability, potentially affecting more than just the renewal itself.
Risks and consequences: Identified gaps during renewal can lead to notices of violation, permit modifications, increased monitoring, enforcement actions, and future scrutiny, often uncovering longstanding issues rather than new violations.
Common issues and affected industries: Problems frequently arise from outdated potential to emit assumptions, monitoring methods, operational changes, or unvalidated permit bases, impacting sectors such as manufacturing, printing, power generation, food production, petroleum, and data centers.
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Vidhya Viswanathan currently serves as Senior Vice President and Director of Engineering for SCS Engineers’ Southwest region and will assume leadership of the solid waste group. She has more than two decades of experience in solid waste management, landfill gas engineering, and compost facility design. She is a licensed Professional Engineer in California, Arizona, Nevada, and Oklahoma and is based in San Diego, CA.
